Island



(No Model.) 2 SheetsSheet 1; 0. D. ROGERS.

' DIE FOR ROLLING DRIVE SCREWS.

No. 408.528. Patented Aug. 6, 1889.

WITNEEEEEI. INVENTEIHI vwys.

UNITED STATES PATENT OFFICE.

CHARLES D. ROGERS, OF PROVIDENCE, RHODE ISLAND, ASSIGNOR TO THE AMERICANSCREW COMPANY, OF SAME PLACE.

DIE FOR ROLLING DRIVE=SCREWS.

SPECIFICATION forming part of Letters Patent No. 408,528, dated August6, 1889.

Application filed February 12, 1889. Serial No. 299,669. (No model.)

To aZZ whmn it may concern: spective view of my improved screw having Beit known that I, CHARLES D. ROGERs,a a slightly-modified form. A portionof this citizen of the United States, residing at Proviscrew is alsobroken away to show the form dence, in the county of Providence andState and arrangement of the grooves and threads,

of Rhode Island, have invented certain new which have a steeperinclination or pitch 55 and useful Improvements in Dies for Rolling thanthe threads shown in Fig. 1, the thread, Wood-Screws; and I do herebydeclare the as drawn in Fig. 4, being what is termed a following to be afull, clear, and exact descripdouble thread and having two continuoustion of the invention, such as will enable othgrooves. Fig. 5 is a crosssectional view ers skilled in the art to which it appertains taken online 0 0 of Fig. 4. Fig. 6 is a front 60 to make and use the same,reference being view of the die, in reduced scale, showingthe had to theaccompanying drawings, and to working-face, the die being moreparticularly letters of reference marked thereon, which adapted toproduce the threads and groove form a part of this specification. shownin Fig. 1. Fig. 7 is an end view of the The invention herein describedrelates to a die. Fig. 8 is an enlarged transverse sectional 65 die forproducing a peculiar wood-screw, for view taken on line m 00 of Fig. 6.Fig. 9 is a which I have this day made an application front view of thedie, also in reduced scale, for a patent. The die must produce 011 thehaving the ribs and grooves arranged to prosurface of ascrew-blanlgfirst, shallow spiral duce the double grooves and threadsshown in grooves having transversely a curved surface; Fig. 4, and Fig.10 is an end view of the die. 70 second; threads at the edges of thegroove In Fig. 1 is illustrated the conditions reraised slightly abovethe normal surface of quired in the die itself, and, as shown in Fig.the blank, and, third, a spiral normal portion 6, the shallow spiralcontinuous groor e a, of the blanks surface between two adjacent havingtransversely a curved form, and the threads. The die is straight,havingits workthreads 0 at the edges of the groove raised 7 5 ing-faceprovided with diagonal ribs, grooves, slightly above the normal surfacem of the and plane surfaces corresponding to the blank, have,respectively, their counterpart grooves, threads, and normal surface ofthe in the diagonal raised ribs a, grooves c, and blank. The ribs rise,in part, above the plane plane surface on of the straight die D. Inorportions of the die, and extend slightlybelow der to produce thethreads and grooveon the 80 those surfaces, forming along the sides ofthe point portion 19 of the screw, Fig. 1, the face ribs grooves whichproduce the thread of the of'the die is raised along its lower edge, asatscrew. The ribs are convex transversely, and 25 Fig. 7. Theinclination of the ribs and in operation are to be forced into the blankgrooves is such as to produce single-groove 3 5 to the extent that theyrise above the plane screws, the blank being entered at the right 85portions of the die-surface. The metal which of the die, the ribs afirst acting upon the is displaced should flow into and fill the pointof the blank and gradually form the grooves formed between the ribs andthe plane groove (1 and threads 0 upon the surface of portions of thedie. The faces of the ribs the blank. The dotted lines or at the sec 40which first come in contact with the blank tional portion of Figs. 1 and4 indicate the 90 should be a little lower than those which comrelativepitch or inclination of the screwplete the grooves, in order that thedisplacethreads. The transverse area of the portion ment of the metalmay be gradual. of a rib at, extending above the general face In theannexed drawings, Figure l repreor surface m of the die, is practicallyequal sents one form of my improved wood-screw, to the area of the twogrooves 0, extending 5 a portion of the screw being in section to belowsaid surface. Consequently the metal show the form of the groove andthreads, one of the blank which is displaced by the ribs of continuousgroove being employed. Figs. 2 the dies should fiow into and just fillthe and 3 are cross-sectional views taken on lines grooves 0, therebyproducing a screw having a: w and w w, respectively. Fig. 4 is a peraspiral groove (4 and screw-threads c, raised :00

at the edges of the groove above the normal surface of the blank, andhaving a spiral normal surface m between the threads.

In producing the screw shown in Fig. 4, and having a double groove, theangle of the ribs and grooves of the die form an inclination of aboutforty-five degrees, as shown in Fig. 9. The ribs a are very short at theend of the die (right) where the rolling commences, and graduallyincrease in length therefrom until the maximum is reached at theopposite end of the die. A pair of dies thus made and suitably mountedwould seize a blank at a point midway of the portion to be threaded andgradually form the grooves and threads therein from said point in eitherdirection simultaneously, the thread produced not extending to thepoint.

As before stated, the face of the ribs at the entering end, which firstcomein contact with the metal, should be a very little lower than thefaces of the ribs farther along, which complete the grooves in thescrew, in order that the displacement of the metal may be gradual. Inthe use of the die the plane portions m should be brought into contactwith the normal surface m of the blank which is to be preserved in orderto prevent its distortion by the displacement of the metal to form thegrooves.

It will be understood that two (lies I) like that described are to beused in making screws, and that the blank is rolled between them as theymove past each other in opposite directions. They are to be operatedin amachine similar to that described in a patent granted to me September20, 1887, No. 370,353, and also in my patent of September 4, 1888, No.389,168.

The amount of metal displaced by the action of the ribs a to form thegroove a and threads 0 is indicated by the dotted line at t, Fig. 3,being a transverse sectional view of the screw represented in Fig. 1,and Fig. 5 shows a corresponding displacement of the metal of the screwshown in Fig. 4.

I claim- A die for rolling screws, provided with diagonal ribs andgrooves for impressing a spiral groove into the metal of a screw-blankand raising the metal at the edges of the groove above the normalsurface of the blank to form the threads of a screw, and with planesurfaces between the ribs corresponding to the normal surface of theblank to preserve such surface from distortion by the action of the ribsin forming the groove and threads.

In testimony whereof I have aifixed my signature in presence of twowitnesses.

CHARLES D. ROGERS.

Witnesses:

CHARLES HANNIGAN, GEO. II. REMINGTON.

